Electronic devices and modules are commonly mounted on printed circuit boards (PCBs). An electronic module, such as an optical transmitter or receiver module, may include a PCB. Mounting such a PCB-based opto-electronic module on a main PCB can be problematic due to narrow spacing between adjacent electrical signal leads.
An opto-electronic module includes an opto-electronic device, such as a semiconductor laser or photodiode, and commonly also includes a driver or receiver integrated circuit chip as well as one or more optical devices such as lenses. The laser converts electrical signals into optical signals. The photodiode converts optical signals into electrical signals. In some types of opto-electronic modules, the opto-electronic device and integrated circuit chip are mounted on a leadframe. In other types of opto-electronic modules, the opto-electronic device and integrated circuit chip are mounted on a module PCB. Wirebonds commonly connect the electronic and opto-electronic devices to the leadframe conductors or PCB circuit traces. The leadframe or module PCB, opto-electronic device, integrated circuit, and wirebonds are commonly encapsulated together in an optically transparent resin that forms a module case. Leadframe conductors or PCB circuit traces are coupled to electrical signal leads that extend from the case along one edge of the leadframe or PCB. Due to the compact size of such opto-electronic modules, the electrical signal leads may be bent and staggered to facilitate connecting them to pads on a main PCB. The electrical signal leads are commonly surface-mounted to the pads on the main PCB.
It is known to mount a secondary PCB (sometimes referred to as a daughterboard) in an orientation perpendicular to a primary or main PCB using a PCB-to-PCB connector comprising a molded plastic retaining block in which electrical leads are encapsulated. One end of each lead is mounted in a through-hole in the main PCB, and the other end of each lead is mounted in a through-hole in the daughterboard PCB. Each lead has a 90-degree bend. The bent portions of the leads are encapsulated in the retaining block. The retaining block can be fixed to the surface of the main PCB with screws or adhesive to provide mechanical integrity to the connection.
Surface-mount leadframes into which the edge of a secondary PCB can be plugged are known. Such a surface-mount leadframe comprises an elongated or bar-shaped conductor in which a socket-like structure has been formed between two opposing surface-mountable ends of the bar-shaped conductor. When the edge of a secondary PCB is plugged into the socket-like structure, an electrical connection is made between a trace or pad on the secondary PCB and the surface-mountable ends. An array of such surface-mounted leadframes can be provided in parallel to accordingly provide electrical contact between multiple secondary PCB circuit traces and corresponding main PCB traces or pads. An array of such surface-mount leadframes can be manufactured by stamping a single sheet of metal and then removing non-functional cross-portions of the metal that serve only to retain the leadframes together during manufacturing.
It would be desirable to provide an improved method for making a leadframe for PCB-based modules.